Compact Multi-Use Lancing Device

ABSTRACT

A multi-use micro-sampling or lancing device ( 10 ) having an outer housing ( 12 ), a lancet holder ( 32 ) that engages a lancet ( 30 ) and constrains the lancet along a controlled and predefined path of travel during the lancing stroke, and a drive mechanism with a pair of opposed, off axis torsion springs ( 80,82 ) working in tandem to drive and return the lancet holder through its lancing stroke.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/549,317, filed Mar. 2, 2004, the entirety ofwhich is hereby incorporated herein by reference for all purposes.

TECHNICAL FIELD

The present invention relates generally to medical devices andprocedures, and more particularly to a multi-use, micro-sampling device.

BACKGROUND OF THE INVENTION

Many medical procedures require puncturing of the skin, and sometimesunderlying tissues, of an animal or human subject. For example, a sharplancet tip is commonly used to puncture the subject's skin at a lancingsite to obtain a sample of blood, interstitial fluid or other bodyfluid, as for example in blood glucose monitoring by diabetics and inblood typing and screening applications.

In some instances, a person must periodically sample their blood formultiple testing throughout the day or week. Thus, due to the nature ofmicro-sampling for blood glucose monitoring, many individuals requiringregular monitoring prefer to do so discretely. Current multi-usemicro-sampling devices tend to have a large, pen-like form thatrestricts the ability of the individual user to conduct micro-samplingdiscretely. Some have attempted to miniaturize the micro-samplingdevice, but the device still has a large and indiscrete size.

Thus it can be seen that needs exist for improvements to lancing devicesto provide a micro-sampling device having a small and discrete size.Needs further exist for such a mechanism that has a smaller overallprofile while remaining compatible with standard lancets commonlyavailable. In addition, needs exist for combining drive elements forcontrol of the lancet travel and return that provide for a wide, yet farshorter, overall shape.

SUMMARY OF THE INVENTION

Briefly described in example forms, the present invention is a multi-usemicro-sampling or lancing device comprising a compact outer housingcontaining drive and activation mechanisms for receiving a disposableand replaceable lancet and for driving the lancet through a controlledlancing stroke for sample collection. The housing preferably includes alancet holder that securely but releasably engages the lancet andconstrains the lancet along a controlled and pre-defined path of travelduring the lancing stroke.

The lancing device preferably includes a drive mechanism including apair of opposed torsion springs to drive and propel the lancet throughan extended position along its lancing stroke, and to return the lancetto a retracted position fully within the housing. This drive mechanismis compact, and thus, the overall size, and particularly the length, ofthe lancing device can be significantly reduced. The lancing device may,for example, have the overall size and shape of a typical automotivedoor-lock remote control keyfob.

In one aspect, the invention comprises a lancing device having a compacthousing, a lancet holder for a holding a lancet and mounted for back andforth movement along a lancing stroke path within the housing, and adrive mechanism comprising at least one off-axis spring coupled to thelancet holder, the at least one off-axis spring being positionedlaterally offset from the lancing stroke path of the lancet holder. Inan example embodiment, the at least one spring comprises a drive springfor driving the lancet holder along the lancing stroke and an opposingreturn spring for returning the lancet holder.

Preferably, the compact housing has a width comparable to the length ofthe housing and is about twice as long as a lancet used therein.Additionally, the lancing device has a trigger to trigger the lancingstroke. Also preferably, the lancet holder is barbed to hold the lancetholder in a ready position, ready for triggering, wherein the barbedlancet holder comprises compression arms each having at least onechamfered barb, and wherein the trigger engages the chamfered barbs totrigger the lancing stroke.

In another aspect, the present invention is a lancing device having acompact housing having a length and a width, with the length of thehousing being roughly the same as the width of the housing; and a drivemechanism within the housing for driving a lancet along a pre-definedpath. The drive mechanism includes a carrier for securely holding thelancet, a first spring for urging the lancet from an initial positioninto an extended position wherein a portion of the lancet protrudes outof the compact housing, and a second spring for retracting the lancetback into the housing. Preferably, the springs are positioned laterallyoffset from the pre-defined path.

In yet another aspect, the present invention is a lancing device havinga compact, non-elongated, puck-like housing, a drive mechanism formovably supporting a lancet along a lancing stroke, a trigger fortriggering the drive mechanism, and wherein the housing has a length ofbetween about two and four times as long as the length of the lancetused therein. Preferably, the housing is about twice as long as thelancet, and has a width roughly equal to its length. Also preferably,the drive mechanism includes off-axis springs for urging the lancet backand forth along the lancing stroke, the off-axis springs being laterallyoffset from the lancing stroke.

These and other aspects, features and advantages of the invention willbe understood with reference to the drawing figures and detaileddescription herein, and will be realized by means of the variouselements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following brief description of the drawings anddetailed description of the invention are exemplary and explanatory ofpreferred embodiments of the invention, and are not restrictive of theinvention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an assembly view of a multi-use lancing device according to anexample embodiment of the present invention.

FIG. 2 is a top view of a lancet holder component of the multi-uselancing device of FIG. 1.

FIG. 3 is a top sectional view of the multi-use lancing device of FIG. 1shown prior to the insertion of a lancet, and with the endcap removed.

FIG. 4 is a top sectional view of the multi-use lancing device of FIG. 1shown having a lancet inserted therein, and with the drive mechanism inits extended “ready” configuration.

FIG. 5 is a detailed view of the inter-engaging locking elements of thelancet holder of FIG. 4.

FIG. 6 is a top sectional view of the multi-use lancing device of FIG. 1shown having a lancet inserted therein, with its protective sterilitycap removed from the lancet.

FIG. 7 is a top sectional view of the multi-use lancing device of FIG.1, shown with its endcap portion attached and having a lancet in theready position.

FIG. 8 is a top sectional view of the multi-use lancing device of FIG.1, showing as the device is activated to release the drive mechanismfrom its ready state.

FIG. 9 is a top sectional view of the multi-use lancing device of FIG.1, shown with the lancet in its extended position wherein the lancet tipprojects outwardly from the device's housing.

FIG. 10 is a top sectional view of the multi-use lancing device of FIG.1, shown with a used lancet drawn back into its retracted position withthe sharp lancet tip fully contained within the housing.

FIG. 11 is a top sectional view of a multi-use lancing device accordingto another example embodiment of the present invention.

FIG. 12 is an assembly view of a multi-use lancing device according toyet another example embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The present invention may be understood more readily by reference to thefollowing detailed description of the invention taken in connection withthe accompanying drawing figures, which form a part of this disclosure.It is to be understood that this invention is not limited to thespecific devices, methods, conditions or parameters described and/orshown herein, and that the terminology used herein is for the purpose ofdescribing particular embodiments by way of example only and is notintended to be limiting of the claimed invention. Also, as used in thespecification including the appended claims, the singular forms “a,”“an,” and “the” include the plural, and reference to a particularnumerical value includes at least that particular value, unless thecontext clearly dictates otherwise. Ranges may be expressed herein asfrom “about” or “approximately” one particular value and/or to “about”or “approximately” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment.

With reference now to the drawing figures, FIG. 1 is an assembly view ofa multi-use micro-sampling device or lancing device 10 according to anexample embodiment of the present invention. The lancing device 10preferably comprises a housing 12 having a top portion 14 connected to abottom portion 16, as by adhesive or crush-pins. An endcap portion 20 ofthe lancing device 10 is removably connected to the housing 12 such thata new lancet can be manually inserted into the device and a used lancetcan be manually removed from the device. The endcap portion 20preferably defines a small opening 22 for protrusion of a sharp lancetneedle or tip therethrough and into the tissue at the intended lancingsite selected by user. At the end of the housing 12 opposite the endcapportion 20 is an opening or channel 24 for receiving an activatingbutton assembly 26 and for guiding the activating button assembly alonga pre-defined path of travel.

A replaceable and disposable lancet 30 is installed in a reciprocatinglancet holder, carrier, or sled 32 within the housing. The lancet 30itself is translationally mounted within the housing 12 forreciprocating movement. The lancet 30 typically comprises a needle orblade forming a sharp lancet tip 34 (see FIGS. 4 and 7, for example) anda lancet body 36, and is positioned such that the tip 34 is directedforward, toward the lancet opening 22 in the endcap portion 20.Preferably, the lancet body 36 is formed of plastic, and isinjection-molded around the needle or blade. The lancet tip 34 ispreferably encapsulated by a protective sterility cap 38, which isintegrally molded with the lancet body 36 and forms a sterility andsafety barrier for the lancet tip. As shown in FIG. 1, the protectivesterility cap 38 of each lancet 30 is releasably connected to the lancetbody 36 at a transition region 40, which is an area of weakening suchthat it is easily detached and removed from the lancet body 36. Thelancet 30 can be, for example, a standard, commercially-available lancetsuch as an Accu-Check® Softclix® lancet.

As more clearly seen in FIG. 2, the lancet holder 32 preferablycomprises two male guide elements, such as upper guide element 42 (forclarity, only one of which is shown) and an opening 46 at one end of thelancet holder 32. The opening 46 is sized and shaped to securely butreleasably hold the replaceable lancet 30. Preferably, the male guideelements are integrally formed on both the upper and lower surfaces ofthe lancet holder 32, and slide within inter-engaging female guidesurfaces 48, 49, such as grooves or channels, formed in the lower andupper portions 16 and 14 of the housing 12, to constrain the lancet 30along a controlled and pre-defined path of travel during the lancingstroke. For clarity, only one of the male guide elements 42 is shown inthe figures, and it will be understood by those skilled in the art, thata female guide surface 49 on the underside of the top portion of thehousing 14 receives and guides the male portion 42. Another male guideelement (not shown) on the underside of the lancet holder 32 engageswith female guide surface 48. It will be understood by those skilled inthe art that a single pair of cooperating guide elements can be used ortwo or more such pairs can be used. Thus, while two pairs of guideelements are shown, fewer or more such pairs can be utilized asdescribed.

The lancet holder 32 preferably has a generally U-shaped portion 52formed by an opposed pair of compression arms 54 and 56, with chamferedbarbs 58 and 60 formed at their distal ends, respectively, for engagingcooperating retaining or locking tabs 62 and 64 integrated within thebottom portion 14 of the housing 12. The retaining tabs 62 and 64 engagethe barbs 58 and 60 to maintain lancet holder 32 in a “ready” positionagainst the bias force of the drive spring when the device 10 is cocked.The ends of the retaining tabs 62 and 64 preferably define chamfers 70and 72 for sliding contact along cooperating chamfered faces 66 and 68of the barbs 58 and 60, to provide a smooth cocking action. Thecompression arms 54 and 56 can resiliently flex inwardly and thus allowmovement of their free ends towards each other upon cocking and firingof the device 10. The barbs 58 and 60 have flat edges 74 and 76 forreleasable engagement against the retaining tabs 62 and 64 in the readyposition.

Preferably, the retaining tabs 62 and 64 are relatively rigid and thecompression arms 54, 56 are flexible. Alternatively, the retaining tabs62, 64 could be made flexible and the arms 54, 56 could be relativelyinflexible (the firing being accomplished by deflecting the retainingtabs). Moreover, both the compression arms and the retaining tabs couldbe flexible.

Referring now to FIGS. 1, 3, 4, 6, 7, 8, 9, and 10, two torsion springs,namely a drive spring 80 and a return spring 82, operate to drive andreturn the lancet holder 32 along the lancing stroke upon triggering ofthe lancing device 10. Together, the drive spring 80, the return spring82, and the lancet holder 32 form a drive mechanism 84 for driving thelancet back and forth along its pre-defined path. The drive spring 80 isthe stronger of the two springs and drives the lancet 30 from itsinitial position into its extended position. The return spring 82 servesto retract the lancet 30 back into the housing 12 after lancing theskin. Preferably, the drive spring 80 and the return spring 82 arelaterally offset from a lancing stroke of the lancet holder 32, and thusare positioned off the axis of the lancet holder so as to provide a morecompact configuration of the lancing device 10. (Of course, the verytips of the springs 80 and 82 contact the lancet holder 32 along thestroke path, but the vast majority of the springs lie outside of thestroke path).

In an example embodiment of the present invention, the device 10 ispuck-like and has a length in the direction of the lancing stroke ofabout 3.5 inches and a width, which is traverse to its length, of about2.875 inches. The device 10 also has a thickness of about 0.5 inch.Thus, the exemplary lancing device 10 has an aspect ratio of about 1.25.The housing could be reconfigured to have an aspect ratio of less than1.0 to about 4 or 5. Additionally, the length of the housing can bebetween about two and four times the length of the lancet used therein.

A pair of posts or lugs 86 and 88 serves as retainers for positioningthe springs 80 and 82, and thereby more precisely defining theequilibrium position of the lancet holder 32. The springs 80 and 82 aresecured within the housing 12 around a pair of axles on pivots 90 and92, respectively, projecting from the bottom portion 14 of the housing.

The lancing device 10 preferably further comprises an activating buttonassembly or trigger 26 positioned at the end of the housing 12 oppositethe endcap portion 20, for triggering the drive mechanism 84 to propelthe lancet 30 through its lancing stroke. An example configuration ofthe trigger 26 preferably includes a button portion 94 having a pair ofposts 96 and 98 on its inner surface which contact the chamfered faces66 and 68 of the compression arms 54 and 56 of the lancet holder 32.When the button 94 is depressed, the posts 96, 98 press inwardly againstthe arms 54 and 56 to release the flat edges 74 and 76 of barbs 58 and60 from engagement with the retaining tabs 62 and 64 to initiate(trigger) the lancing action. The trigger 26 preferably furthercomprises a coil spring 100, which is positioned between a spring postor stop 102 extending from bottom portion 16 of the housing 12 and thebutton 94, thereby biasing the button 94 outwardly.

The opposed torsion spring drive mechanism 84 permits a significantreduction in the overall size (and especially the length) of the lancingdevice 10, as compared to typical known lancing devices. Thus, theoverall size of the lancing device 10 may be a bit wider thanconventional lancing devices, but the length of the device 10 is muchshorter. With this reduced size, the lancing device 10 can accommodateother elements, such as an adjustable depth-control ring (forcontrolling the penetration depth of the lancet into the user's skin), alancet storage feature, or other similar optional features, withoutresulting in an objectionably large device.

FIG. 3 shows a top sectional view of the multi-use lancing device 10prior to insertion of the lancet 30 therein. The lancet holder 32 is notcocked, and thus the lancet holder is considered to be in a “withdrawn”or “steady” state. In this “withdrawn” state, the activating button 94and the coil spring 100 are fully retracted. Thus, the coil spring 100is positioned against the spring post 102 of the bottom portion 16. Thereturn torsion spring 82 is in a retracted compression state, or its“equilibrium” or “steady” state, and opposes the “equilibrium” or“steady” position of the drive spring 80. The drive torsion spring 80 isalso in a forward compression state, or its “steady” compression state.In this position, the drive spring 80 and return spring 82counter-balance one another, and the lancet holder 32 is in anequilibrium position.

When the device 10 is in its “equilibrium” state, a user manually loadsa new lancet 30 (with its protective cap still in place) into the lancetholder 32 and pushes the lancet holder back (i.e., towards theactivation button assembly 26), until the barbs 58 and 60 of the lancetholder snap into engagement with the lancet holder retaining tabs 62 and64, thereby placing the device in its “cocked” or “ready” position. Oncethe device is thusly cocked, the user would remove the protectivesterility cap 38.

FIG. 4 shows the lancing device 10 without the endcap portion 20 andhaving a lancet 30 inserted therein. The lancet 30 is shown with itsprotective cap 38 still connected to its body 36. The return torsionspring 82 is in its non-compressed or “relaxed” state, and the drivetorsion spring 80 is in its fully-extended or “ready” state. Thus, abiasing force is applied by the extended drive spring 80 on the lancetholder 32 in the forward direction (i.e., toward the lancet tip 34). Theactivating button assembly 26 is in its “steady” state. As seen moreclearly in FIG. 5, the flat edges 74 and 76 of the barbs 58 and 60 ofthe lancet holder 32 are in engagement with the retaining tabs 62 and64, thus holding the drive mechanism 84 in its cocked or “ready” state.The user manually removes the protective sterility cap 38 from thelancet body prior to replacing the endcap 20.

FIG. 6 shows the multi-use lancing device 10 having the lancet 30inserted therein and with its protective sterility cap 38 manuallyremoved, thereby exposing the lancet tip 34. Once the protectivesterility cap 38 has been removed, the user then replaces the endcapportion 20. FIG. 7 shows the lancing device 10 with its endcap portion20 in place. The user then places the opening 22 of the lancing device10 against his or her skin at the desired lancing site, and presses thebutton 94 to fire or “activate” the lancing device.

FIG. 8 shows the lancing device 10 as the device is being triggered or“activated”. The lancing device 10 is activated when the activatingbutton 94 is pressed. As the button 94 is pressed, the channel 24 in thehousing 12 guides the movement of the activating button 94 duringcompression of the spring 100. Posts 96 and 98 engage the chamferedfaces 66 and 68 of the compression arms 54 and 56 of the lancet holder32, to flex the arms inwardly and release the barbs 58 and 60 fromretaining tabs 62 and 64, initiating the lancing action. Because thedrive spring 80 is stiffer than the return spring 82, the lancet 30 isdriven forward into its extended position. The lancet 30 moves into itsextended position, wherein its tip 34 punctures the user's skin at thelancing site, and then is withdrawn back to a retracted position wherethe tip is shielded within the housing 12.

FIG. 9 shows the lancing device 10 with the lancet tip 34 in itsextended position, projecting through the opening 22 of the endcapportion 20. The lancet 30 and the lancet holder 32 are in their fullyextended positions when the male guide element 42 of the lancet holder32 traverses the length of the cooperating female portion 48, andconsequently, a forward face of the lancet body 36 contacts an innersurface 104 of the endcap portion 20. In alternate embodiments, theendcap 20 optionally includes a depth adjustment mechanism (unshown)permitting the user to selectively vary the position of the stop surface104. Upon release of the activating button assembly 26 the retractionspring 100 biases the activating button 94 back to its initial position.The return torsion spring 82 is extended, and the drive spring 80 isrelaxed, thereby imparting a force to bias the lancet holder 32 backtoward its withdrawn position. Once the lancing procedure is completed,the tip 34 of the lancet 30 is drawn back into the lancing device 10,and the user removes the lancing device from the lancing site so as toobtain a sampling of blood or other bodily fluid.

FIG. 10 shows the multi-use lancing device 10 with the used lancet 30drawn back into its withdrawn position, fully within the housing. Thesprings 80 and 82 have returned to their equilibrium or “steady” state.The endcap portion 20 of the lancing device 10 can now be detached sothat the used lancet 30 can be removed and a new lancet can be inserted.As seen in FIG. 9, the activating button assembly 26 including theretraction spring 100 has returned to its “steady” state such that theactivating button 94 is fully retracted.

FIG. 11 shows a multi-use lancing device 110 according to anotherexample embodiment of the present invention. The lancing device 110 issubstantially similar to the lancing device 10 with the exception of theorientations of the drive torsion spring 180 and return torsion spring182. The lancet holder 132 is shown in its “steady” state, with springs180 and 182 in equilibrium. When the device 110 is cocked to place thelancet holder 132 in the ready position, the drive spring 180 iscompressed to apply force on the lancet holder in the forward direction,and the return spring 182 is relaxed. When the device 110 is activatedto release the lancet holder 132 and the lancet moves to its extendedposition, the return spring 182 is compressed to apply rearward force onthe lancet holder 132, and the drive spring 180 is relaxed. The springs180 and 182 then return to equilibrium with the lancet holder 132 backin its retracted position within the housing 112. Thus, in the device ofFIG. 11, the energized states of the drive torsion spring 180 and thereturn torsion spring 182 are compressed in the “coil” directions toprovide biasing force on the lancet holder 132; whereas in FIGS. 1-10,the energized states of the springs 80 and 82 are extended in the“reverse coil” directions. A pair of posts or lugs 186 and 188 serve asretainers to position the springs 180 and 182, and thereby moreprecisely define the equilibrium position of the lancet holder 132.

FIG. 12 depicts an alternate embodiment of the lancing device 210. Thelancing device 210 is substantially similar to the lancing device 10,but with the exceptions noted herein. The lancing device 210 has ahousing 212 having a top portion 214 and a bottom portion 216. A slot250 is located within top portion 212, and a corresponding slot islocated within the bottom portion 216. A lancet holder or sled 232 holdsa lancet 30 securely therein. Male guide elements 242 are integrallyformed on both the upper and lower surfaces of the lancet holder andextend through and slide within slots 250 and 252.

To operate the device 210, the user inserts a lancet 30 into the opening246 of the lancet holder 232, and removes the sterility cap 38 from thelancet body 36. The user replaces the endcap portion 220. To activatethe device, the user pushes (or pulls) the male guide elements 242towards the rear of the device (i.e., towards the button 294). This inturn activates or cocks the device because the barbs 258 and 260 engagethe locking tabs 262 and 264, which in turn holds the lancet holder 232in a “ready” position.

While the invention has been described with reference to preferred andexample embodiments, it will be understood by those skilled in the artthat a variety of modifications, additions and deletions are within thescope of the invention, as defined by the following claims.

1. A lancing device comprising: a housing; a lancet holder for a holdinga lancet and mounted for back and forth movement along a lancing strokepath within the housing; and a drive mechanism comprising a pair ofoff-axis springs coupled to the lancet holder, each of the pair ofoff-axis springs being positioned laterally offset from the lancingstroke path of the lancet holder.
 2. The lancing device of claim 1,wherein the housing has a width comparable to the length of the housing.3. The lancing device of claim 1, further comprising a trigger totrigger the lancing stroke.
 4. The lancing device of claim 3, whereinthe lancet holder is barbed to hold the lancet holder in a readyposition, ready for triggering.
 5. The lancing device of claim 4,wherein the barbed lancet holder comprises compression arms each havingat least one chamfered barb, and wherein the trigger engages thechamfered barbs to trigger the lancing stroke.
 6. The lancing device ofclaim 1, wherein the pair of off-axis springs comprises a first torsionspring for advancing the lancet holder along the lancing stroke and asecond torsion spring for retracting the lancet holder.
 7. The lancingdevice as claimed in claim 1, wherein the housing is about twice as longas a lancet used therein.
 8. A lancing device, comprising: a housing; adrive mechanism within the housing for driving a lancet along apre-defined path, the drive mechanism comprising: a carrier for securelyholding the lancet; a first torsion spring for urging the lancet from aninitial position into an extended position wherein a portion of thelancet protrudes out of the compact housing; and a second torsion springfor retracting the lancet back into the housing.
 9. The lancing deviceof claim 8, further comprising a trigger for triggering the drivemechanism.
 10. The lancing device of claim 8, wherein the springs arepositioned laterally offset from the pre-defined path.
 11. The lancingdevice of claim 8, wherein the length of the housing is between abouttwo and four times the length of the lancet used therein.
 12. A lancingdevice, comprising: a compact, non-elongated housing; a drive mechanismfor movably supporting a lancet along a lancing stroke; a trigger fortriggering the drive mechanism; and wherein the housing has a length ofno more than about four times as long as the length of the lancet usedtherein.
 13. The housing of claim 12, wherein the housing is about twiceas long as the lancet.
 14. The lancing device of claim 12, wherein thehousing has a width roughly equal to its length.
 15. The lancing deviceof claim 12, wherein the housing is puck-like.
 16. The lancing device ofclaim 12, wherein the drive mechanism includes off-axis springs forurging the lancet back and forth along the lancing stroke, the off-axissprings being laterally offset from the lancing stroke.
 17. A method ofcollecting a sample of fluid, comprising: inserting a lancet into acarrier of a multi-use sampling device; aligning an opening of thedevice at a site to be lanced; pressing an activating button having apost for contacting a chamfered barb of the carrier to release thecarrier; and collecting a sample of fluid.
 18. The method of claim 17,wherein the step of inserting a lancet into a carrier further includespushing the lancet towards the rear of the device until the chamferedbarb of the carrier locks into a ready position.
 19. A lancing devicecomprising: a reciprocating lancet carrier for releasably engaging areplaceable lancet, the lancet carrier traversing a linear path oftravel along a forward stroke and a return stroke; and a pair of torsionsprings operating in tandem to advance the lancet carrier along theforward stroke, and to retract the lancet carrier along the returnstroke.
 20. The lancing device of claim 19, wherein each of the pair oftorsion springs is laterally offset from the path of travel of thelancet carrier.
 21. The lancing device of claim 19, wherein the pair oftorsion springs comprise a drive spring and a return spring, the drivespring being stiffer than the return spring.
 22. The lancing device ofclaim 19, wherein the pair of torsion springs are positioned on oppositesides of the path of travel of the lancet carrier.
 23. The lancingdevice of claim 19, wherein the lancet carrier comprises at least onearm extending therefrom, for retaining the lancet carrier in a cockedposition until released by a triggering member.
 24. The lancing deviceof claim 19, wherein the lancet carrier comprises at least one guideelement for constraining motion of the lancet carrier to the linear pathof travel.
 25. The lancing device of claim 24, wherein free ends of thetorsion springs engage against the at least one guide element to advanceand retract the lancet carrier.